Don’t upset the apple cart

Do you know the English proverb “Don’t upset the apple cart“? Read the conversation below. Can you guess the meaning?

Natalie: I’m going to suggest a new way of working in the meeting tomorrow. I think people will work better and faster if they try my way of working.

Greg: Don’t upset the apple cart. Everyone has been working here longer than you. They don’t like change. The last time someone suggested a change in the way of working, it caused a lot of problems. The boss is happy with the way we work now.

Does it mean

a) Don’t disturb things. Leave things as they are

b) Don’t damage the apples

c) Don’t make people angry

d) Don’t upset the boss

The answer is below ↓

Answer: a) Don’t disturb things. Leave things as they are